The present invention relates to a method and apparatus for obtaining the size and shape of a foot from a scan of an imprint of the foot for use in manufacturing orthotic shoes and sandals and orthotic inserts to a shoe.
In many instances, it is necessary to provide an orthotic/orthopedic shoe insert, or a shoe, sandal or other footwear which is customized to meet a particular wearer""s needs. For example, in some instances it is necessary to provide an insert which compensates for differences in the lengths of the legs of a human.
It is desirable for the footwear, such as the shoe itself or an insert for the shoe, to accurately mate with the wearer""s foot. The two feet of a wearer may be different from one another, however, and both feet of one person may vary substantially from the feet of another person. Therefore, the shape, including the width, length, depth and curvature of one or both of the feet of the person must be accurately determined for use in preparing the shoe or insert.
Current methods for determining the size and shape of the foot are imprecise and slow. For example, the size of the foot may be measured with a mechanical measuring device, and the shape estimated using templates. The error introduced in these methods often renders the orthotic or shoe unsatisfactory. In addition, this foot size and shape data is difficult to utilize when manufacturing the orthotic.
The present invention generally comprises a method and apparatus for determining the shape and dimensions of a human foot. One embodiment of the invention comprises a method of determining the shape and size of a foot comprising the steps of obtaining an imprint of the foot, scanning the imprint of the foot to obtain pixel image data regarding the foot imprint at one or more points, determining at said one or more points the depth of the imprint from the pixel image data, and determining a size of said foot from the pixel image data.
In one embodiment, the step of obtaining an imprint of the foot comprises the step of a person stepping onto a foam member and compressing a portion of the foam member. In one embodiment, an imprint may be created of both feet of a person.
In one embodiment, the step of scanning the imprint generates RGB (red, green, blue) pixel image data. The RGB data is converted to YIQ image data. The depth of the imprint at a point is determined from the luminance or Y value of the pixel data for a point.
In one embodiment, the depth is calculated as a linear function of the Y value and a slope of the Y value at that point. In this calculation, coefficients are used to accurately determine the depth value. In one embodiment, the coefficients are determined using a method of least squares to minimize the average error. In another embodiment, the coefficients may be determined by physically measuring the depth of the imprint and calculating the coefficient values from the known data.
In one or more embodiments, foot size information is determined from the image data. In one embodiment, an original scan image of the imprint is passed through a filter. The filtered image is utilized to generate an enhanced original image. The edge and sharp transition areas of the imprint, and thus the foot, are enhanced in this image. The visually enhanced edge areas aid in defining the start and/or end points for distance or xe2x80x9csizexe2x80x9d measurements.
In accordance with the invention, the curvature of one or more areas of the foot may be determined. In one embodiment, the curvature of the arch is determined.
In accordance with the invention, the size and shape of a foot may be determined from an image scan of an imprint of the foot. The size and shape data may be used to create an orthotic, shoe or other member which mates accurately with the foot. In one embodiment, the information may be transmitted, compressed and transmitted, stored or the like. For example, the foot size and shape data may be stored for comparison against later data so that changes in the size and shape of a person""s foot may be determined.